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ARS Home » Southeast Area » Poplarville, Mississippi » Southern Horticultural Research Unit » Research » Publications at this Location » Publication #331542
Title: Integrated varroa control in honey bee colonies (Apis mellifera carnica) with or without brood

Author
item GREGOORC, ALES - Mississippi State University
item Adamczyk, John
item KAPUN, STANKO - University Of Ljubljana
item PLANINC, IVO - University Of Ljubljana

Submitted to: Journal of Apicultural Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/25/2016
Publication Date: 9/9/2016
Citation: Gregoorc, A., Adamczyk Jr, J.J., Kapun, S., Planinc, I. 2016. Integrated varroa control in honey bee colonies (Apis mellifera carnica) with or without brood. Journal of Apicultural Research. 55:253-258.

Interpretive Summary: Studies were conducted in two apiaries in order to assess the comparative efficacy of the soft pesticides, oxalic acid (OA), formic acid (FA) and Thymovar against parasitic varroa mites in honey bee colonies. Consecutive short term FA treatments proceeding Thymovar application, resulted in an average varroa mortality of only 11 and 18%, respectively. Mortality rates in FA and OA treated colonies were slightly greater, ranging between 34-42%. OA treatment in colonies without immature bees (broodless), after caging the queens for 25 days, reduced the varroa population by 11%. Also consecutive OA treatments reduced varroa populations by 11, 24, 16% and the final autumn reduction was 77%, respectively. In the second experiment using broodless colonies by caging and isolating the queens, initial OA treatments caused 24% varroa mortality, however three additional autumn OA treatments resulted in 97% varroa efficacy. These studies found that consecutive Thymovar or OA treatments in colonies with brood have a limited effect on reducing varroa mites. Solely caging the queens and obtaining broodless conditions was also not sufficient for effectively reducing the varroa mites in colonies during summer months. We conclude that a combination of different treatment protocols, using additional control means, can ensure an effective varroa control in colonies.

Technical Abstract: Studies were conducted in two apiaries in order to assess the comparative efficacy of oxalic acid (OA), formic acid (FA) and Thymovar against varroa mites in honey bee colonies. Treatments were performed using 85% FA and OA consisted of 2.9% oxalic acid dihydrate and 31.9% sugar in water. Consecutive short term FA treatments proceeding Thymovar application, resulted in an average varroa mortality of 11 and 18%, respectively. These varroa mortalities were higher than that in the pre-treatment period (P < 0.05). Mortality rates in FA and OA treated colonies were 42% and 34% of the total varroa counts. OA treatment in broodless colonies, after caging the queens for 25 days, reduced the varroa population by 11%. Also consecutive OA sublimations reduced varroa populations by 11, 24, 16% and the final autumn reduction was 77%, respectively. In the second experiment using broodless colonies by caging and isolating the queens, initial OA treatments caused 24% varroa mortality, however three additional autumn OA treatments resulted in 97% varroa efficacy. These studies found that consecutive Thymovar or OA treatments in colonies with brood have a limited effect on reducing varroa mites. Solely caging the queens and obtaining broodless conditions was also not sufficient for effectively reducing the varroa mites in colonies during summer months. We conclude that a combination of different treatment protocols, using additional organic means, can ensure an effective varroa control in colonies.